Modern internal combustion engines are designed to achieve the objectives of low weight, low cost, and high efficiency. Often, these objectives compete with each other such that meeting one objective can result in the failure to meet another objective. For example, modern engine designers aim to achieve a high efficiency engine by increasing the peak cylinder pressure (PCP) capability of the engine. However, in view of the high forces generated by high PCP that are placed on the components of the engine, stronger materials and/or greater mass of materials are required. In most cases, stronger materials also are heavier. Therefore, it is difficult for modern engines to be highly efficient, while also being lightweight. Additionally, lightweight materials such as aluminum tend to have relatively poor fatigue strength, which further limits its viability in high PCP engines.
In view of the above constraints, some engines attempt to avoid the fatigue associated with lighter materials by utilizing a through-bolt scheme that maintains a block made from a lightweight material in compression. However, conventional through-bolt schemes are not conducive to many internal engine lubrication arrangements. For example, the positioning of through-bolts through cylinder blocks generally traverses normal lubrication distribution channels and may block or impede the flow of lubrication through those channels to important components of the engine, such as the main crankshaft journal.
Additionally, typical internal lubrication arrangements for common internal combustion engines tend to result in parasitic losses in the lubrication pump due to high pump-out pressure required to maintain lubrication pressure at the extremities of the lubrication circuit. Moreover, many internal lubrication schemes result in substantial draining of lubrication from the lubrication circuit upon engine shut-down, which causes lubrication shortages and lubrication priming delays within the engine upon start-up.